Experimental Study On Dilute Hydrochloric Acid In The Extraction Of Rare Earth Saponification By N235 Extracting Resin

At current,the separation process of rare earth saponification would produce a large number of ammonia nitrogen wastewater or highsalt wastewater,and Saponification-free extraction technology from the source could solve the problem of waste water extraction.In this paper,based on previous research of the P507-N235 double solvent no saponification extraction of rare earth,preparation of N235 resined,proposed the new technology of N235 resined-P507 no saponification extraction of rare earth,which expected to achieve P507 no saponification of rare earth extraction,avoided risk of P507-N235 double solvent no saponification extraction technology used in the investment and serious loss of organic phase.The main work and research results are as follows:First,carried out the N235 levextrel resin-P507 no saponification extraction rare earth experiment,the results show that the rare earth concentration in P507 can reach 0.18 mol·L^-1 by four times of continuous extraction of rare earth with the initial rare earth concentration is 0.7740 mol·L^-1 and the ratio of?O:A?=1:6.N235 levextrel resin adsorption HCl fast,the equilibrium time is 1.5 h,the maximum adsorption equilibrium capacity of up to 2.84 mol · Kg^-1,desorption liquid pH greater than 5,is an ideal deacidification material.Experiments show that N235 levextrel resin-P507 saponification extraction rare earth process is feasible.Thermodynamics and kinetics of adsorption HCl by N235 extraction resin was studied by static adsorption method?The law of adsorption was discussed.The results show that adsorption of N235 levextrel resin for HCl are in accordance with Langmuir and Freundlich isothermal adsorption equation but the former is better.The maximum adsorption amount of the levextrel resin is 0.3672 mmol·g^-1 at T is 323 K and HCl concentrate of 74.13 mmol·L^-1.The thermodynamic parametes calculating are that?H=18.066 K J·mol^-1??S=65.1 J·?mol·K?^-1??G_303K=^-1.659 KJ·mol^-1??G_308K=^-1.985 KJ·mol^-1??G_313K=-2.31 KJ·mol^-1??G_318K=-2.636 KJ·mol^-1 basis on the previous experiment date.It shows that the adsorption process of N235 levextrel resin for HCl is a endothermic??H>0?,entropy increase??S>0?and spontaneous physical adsorption(?G?-20-0 kJ·mol^-1)process.Adsorption kinetics study results show that adsorption process corresponds to quasi two stage kinetic equation?R2>0.99?and is controlled by the film diffusion.The adsorption and desorption characteristics of N235 resin on dilute HCl solution were investigated by static adsorption method and dynamic adsorption method.The adsorption equilibrium constant was obtained by static adsorption experiment.The results of dynamic adsorption showed that the adsorption flow rate,the resin column height,the HCl concentration,the chloride concentration in the solution,the downstream flow/countercurrent mode would affect the resin equilibrium adsorption capacity;the concentration of hydrochloric acid in the adsorbent,the amount of resin packed,the concentration of rare earth chloride in the adsorbent and the initial concentration of hydrochloric acid in the solution were positively correlated;Besides,the maximum concentration of HCl solution obtained by the adsorption and desorption of N235 resin on dilute HCl solution is less then the initial concentration of adsorbate,and has obvious "memory effect".